This invention relates in general to bearings and more particularly to an antifriction bearing assembly that is cooled by a refrigerant and a process for cooling such a bearing.
Of all the antifriction bearings, tapered rollers are the best suited for use in precision machine tools, particularly for supporting the spindles of such tools. These bearings can carry extremely heavy loads, and are very durable. Furthermore, when mounted in pairs, the two bearings of the pair may be adjusted one against the other to eliminate radial and axial play, and this, of course, provides an extremely stable mounting for the spindle.
Despite these advantages, tapered roller bearings, like other types of bearings, generate heat during operation, with the primary source of this heat being the region of contact between the roller bodies and the raceways, although some heat derives from the friction between the large end faces of the rollers and the thrust rib against which they bear. This heat soaks into the bearing components and the surrounding components of the machine tool and causes those components to undergo dimensional changes. Lubrication systems exist for reducing the friction to the extent that it will not damage the bearing nor require excessive power to turn the spindle, but these systems do not adequately control the temperature, at least to the extent that the temperature remains substantially constant during the operation of the machine tool, that is, from start up through a wide range of speeds. Indeed, to avoid dimensional changes, the bearings should operate at or near room temperature irrespective of the speed of the spindle.